International consensus recommendations on key outcome measures for organ preservation after (chemo)radiotherapy in patients with rectal cancer

Multimodal treatment strategies for patients with rectal cancer are increasingly including the possibility of organ preservation, through nonoperative management or local excision. Organ preservation strategies can enable patients with a complete response or near-complete clinical responses after radiotherapy with or without concomitant chemotherapy to safely avoid the morbidities associated with radical surgery, and thus to maintain anorectal function and quality of life. However, standardization of the key outcome measures of organ preservation strategies is currently lacking; this includes a lack of consensus of the optimal definitions and selection of primary end points according to the trial phase and design; the optimal time points for response assessment; response-based decision-making; follow-up schedules; use of specific anorectal function tests; and quality of life and patient-reported outcomes. Thus, a consensus statement on outcome measures is necessary to ensure consistency and facilitate more accurate comparisons of data from ongoing and future trials. Here, we have convened an international group of experts with extensive experience in the management of patients with rectal cancer, including organ preservation approaches, and used a Delphi process to establish the first international consensus recommendations for key outcome measures of organ preservation, in an attempt to standardize the reporting of data from both trials and routine practice in this emerging area.

Organ Preservation in Rectal Cancer: The Patients' Perspective

Organ preservation after a clinical complete response to radiochemotherapy is currently one of the most discussed topics in the management of rectal cancer. However, the patients' perspective has only been poorly studied so far. In this multicenter study, we examined 49 patients with locally advanced rectal cancer. The willingness to participate in an organ preservation study and the acceptance of the associated aspects such as intensified radiochemotherapy protocols, the need for close follow-up examinations and local regrowth rates were assessed. Attitudes were correlated with baseline quality of life parameters and psychological scales for "fear of progression", "locus of control", "depression", and the "willingness to take risks". A total of 83% of patients would consider the deferral of surgery in case of a clinical complete response (cCR). Three monthly follow-up studies and a 25% local regrowth rate are considered acceptable by 95% and 94% respectively. While 41% would be willing to exchange cure rates for a non-operative treatment strategy, a potentially more toxic radiochemotherapy in order to increase the probability of a cCR was the aspect with the lowest acceptance (55%). Psychological factors, in particular "locus of control" and "willingness to take risks", influenced patient preferences regarding most of the assessed parameters. While in general a broad acceptance of an organ-preserving treatment can be expected, patient preferences and concerns regarding different aspects of this strategy vary widely and require specific consideration during shared decision making.

Impact of curative radiotherapy on the immune status of patients with localized prostate cancer

Combination of radiotherapy with immunotherapy has become an attractive concept for the treatment of cancer. The objective of this study was to assess the effect of curative, normofractionated radiotherapy on peripheral immune lymphocytes in prostate cancer patients, in order to propose a rationale for scheduling of normofractionated radiotherapy with T-cell based immunotherapy. In a prospective study (clinicaltrials.gov: NCT01376674), eighteen patients with localized prostate cancer were treated with radiotherapy with or without hormonal therapy. Irradiation volumes encompassed prostate and, in select cases, elective pelvic nodal regions. Blood samples were collected from all patients before, during, and after radiotherapy, as well as from 6 healthy individuals as control. Normofractionated radiotherapy of prostate cancer over eight weeks had a significant influence on the systemic immune status of patients compared to healthy controls. Absolute leukocyte and lymphocyte counts decreased during treatment as did peripheral blood immune subsets (T cells, CD8+ and naïve CD4+ T cells, B cells). Regulatory T cells and NK cells increased. Proliferation of all immune cells except regulatory T cells increased during RT. Most of these changes were transient. Importantly, the functionality of T lymphocytes and the frequency of antigen-specific CD8+ T cells were not affected during therapy. Our data indicate that combination of normofractionated radiotherapy with immunotherapy might be feasible for patients with prostate cancer. Conceptually, beginning with immunotherapy early during the course of radiotherapy could be beneficial, as the percentage of T cells is highest, the percentage of regulatory T cells is lowest, and as the effects of radiotherapy did not completely subside 3 months after end of radiotherapy.

Prospective evaluation of a hydrogel spacer for rectal separation in dose-escalated intensity-modulated radiotherapy for clinically localized prostate cancer

BACKGROUND

As dose-escalation in prostate cancer radiotherapy improves cure rates, a major concern is rectal toxicity. We prospectively assessed an innovative approach of hydrogel injection between prostate and rectum to reduce the radiation dose to the rectum and thus side effects in dose-escalated prostate radiotherapy.

METHODS

Acute toxicity and planning parameters were prospectively evaluated in patients with T1-2 N0 M0 prostate cancer receiving dose-escalated radiotherapy after injection of a hydrogel spacer. Before and after hydrogel injection, we performed MRI scans for anatomical assessment of rectal separation. Radiotherapy was planned and administered to 78 Gy in 39 fractions.

RESULTS

From eleven patients scheduled for spacer injection the procedure could be performed in ten. In one patient hydrodissection of the Denonvillier space was not possible. Radiation treatment planning showed low rectal doses despite dose-escalation to the target. In accordance with this, acute rectal toxicity was mild without grade 2 events and there was complete resolution within four to twelve weeks.

CONCLUSIONS

This prospective study suggests that hydrogel injection is feasible and may prevent rectal toxicity in dose-escalated radiotherapy of prostate cancer. Further evaluation is necessary including the definition of patients who might benefit from this approach.

TRIAL REGISTRATION

German Clinical Trials Register DRKS00003273.

MR-Guided Radiotherapy for Liver Malignancies

MR guided radiotherapy represents one of the most promising recent technological innovations in the field. The possibility to better visualize therapy volumes, coupled with the innovative online adaptive radiotherapy and motion management approaches, paves the way to more efficient treatment delivery and may be translated in better clinical outcomes both in terms of response and reduced toxicity. The aim of this review is to present the existing evidence about MRgRT applications for liver malignancies, discussing the potential clinical advantages and the current pitfalls of this new technology.

Neutrophil-to-Lymphocyte Ratio in Rectal Cancer-Novel Biomarker of Tumor Immunogenicity During Radiotherapy or Confounding Variable?

The aim of this study was to investigate the predictive value of blood-derived makers of local and systemic inflammatory responses on early and long-term oncological outcomes. A retrospective analysis of patients with locally advanced rectal cancer treated with preoperative long-course 5-fluorouracil-based radiochemotherapy was performed. Differential blood counts before neoadjuvant treatment were extracted from the patients' electronic charts. Optimal cut-off values for neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR) were determined. Potential clinical and hematological prognostic factors for disease-free survival (DFS) were studied using uni- and multivariate analysis. A total of 220 patients were included in the analysis. Median follow-up was 67 months. Five-year DFS and overall survival (OS) were 70% and 85%, respectively. NLR with a cut-off value of 4.06 was identified as optimal to predict DFS events. In multivariate analysis, only tumor volume (HR 0.33, 95% CI (0.14-0.83), p = 0.017) and NLR (HR 0.3, 95% CI (0.11-0.81), p = 0.017) remained significant predictors of DFS. Patients with a good histological response (Dworak 3 and 4) to radiotherapy also had a lower NLR than patients with less pronounced tumor regression (3.0 vs. 4.2, p = 0.015). A strong correlation between primary tumor volume and NLR was seen (Pearson's r = 0.64, p < 0.001). Moreover, patients with T4 tumors had a significantly higher NLR than patients with T1-T3 tumors (6.6 vs. 3.3, p < 0.001). An elevated pretherapeutic NLR was associated with higher T stage, inferior DFS, and poor pathological response to neoadjuvant radiochemotherapy. A strong correlation between NLR and primary tumor volume was seen. This association is important for the interpretation of study results and for the design of translational studies which are warranted.

Quantitative magnetic resonance imaging on hybrid magnetic resonance linear accelerators: Perspective on technical and clinical validation

Many preclinical and clinical observations support that functional magnetic resonance imaging (MRI), such as diffusion weighted (DW) and dynamic contrast enhanced (DCE) MRI, might have a predictive value for radiotherapy. The aim of this review was to assess the current status of quantitative MRI on hybrid MR-Linacs. In a literature research, four publications were identified, investigating technical feasibility, accuracy, repeatability and reproducibility of DW and DCE-MRI in phantoms and first patients. Accuracy and short term repeatability was < 5% for DW-MRI in current MR-Linac systems. Consequently, quantitative imaging providing accurate and reproducible functional information seems possible in MR-Linacs.

Electronic Patient-Reported Outcome Measures in Radiation Oncology: Initial Experience After Workflow Implementation

Background

Mobile health (mHealth) technologies are increasingly used in various medical fields. However, the potential of mHealth to improve patient care in radiotherapy by acquiring electronic patient reported outcome measures (ePROMs) during treatment has been poorly studied so far.

Objective

The aim of this study was to develop and implement a novel Web app (PROMetheus) for patients undergoing radiotherapy. Herein, we have reported our experience with a focus on feasibility, patient acceptance, and a correlation of ePROMs with the clinical course of the patients.

Methods

In the period between January and June 2018, 21 patients used PROMetheus to score side effects, symptoms, and quality of life–related parameters during and after their treatment. Items of the Patient Reported Outcome version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE) were chosen based on the primary site of disease, 27 items for head and neck tumors, 21 items for thoracic tumors, and 24 items for pelvic tumors.

Results

In total, 17 out of the 21 patients (81%) regularly submitted ePROMs and more than 2500 data points were acquired. An average of 5.2, 3.5, and 3.3 min was required to complete the head and neck, thorax, and pelvis questionnaires, respectively. ePROMS were able to detect the occurrence of both expected and unexpected side effects during the treatment.

In addition, a gradual increase in the severity of side effects over the course the treatment and their remission afterward could be observed with ePROMs. In total, 9 out of the 17 patients (53%), mostly those with head and neck and thoracic cancers, reported PRO-CTCAE grade III or IV fatigue with severe impairments of activities of daily life.

Conclusions

This study shows the successful implementation of an ePROM system and a high patient acceptance. ePROMs have a great potential to improve patient care in radiotherapy by providing a comprehensive documentation of symptoms and side effects, especially of ones that are otherwise underreported.

Marker-less online MR-guided stereotactic body radiotherapy of liver metastases at a 1.5 T MR-Linac - Feasibility, workflow data and patient acceptance

INTRODUCTION

Stereotactic body radiotherapy (SBRT) is an established ablative treatment for liver tumors with excellent local control rates. Magnetic resonance imaging guided radiotherapy (MRgRT) provides superior soft tissue contrast and may therefore facilitate a marker-less liver SBRT workflow. The goal of the present study was to investigate feasibility, workflow parameters, toxicity and patient acceptance of MRgSBRT on a 1.5 T MR-Linac.

METHODS

Ten consecutive patients with liver metastases treated on a 1.5 T MR-Linac were included in this prospective trial. Tumor delineation was performed on four-dimensional computed tomography scans and both exhale triggered and free-breathing T2 MRI scans from the MR-Linac. An internal target volume based approach was applied. Organ at risk constraints were based on the UKSABR guidelines (Version 6.1). Patient acceptance regarding device specific aspects was assessed and toxicity was scored according to the common toxicity criteria of adverse events, version 5.

RESULTS

Nine of ten tumors were clearly visible on the 1.5 T MR-Linac. No patient had fiducial markers placed for treatment. All patients were treated with three or five fractions. Median dose to 98% of the gross tumor volume was 38.5 Gy. The median time from "patient identity check" until "beam-off" was 31 min. Median beam on time was 9.6 min. Online MRgRT was well accepted in general and no treatment had to be interrupted on patient request. No event of symptomatic radiation induced liver disease was observed after a median follow-up of ten month (range 3-17 months).

CONCLUSION

Our early experience suggests that online 1.5 T MRgSBRT of liver metastases represents a promising new non-invasive marker-free treatment modality based on high image quality, clinically reasonable in-room times and high patient acceptance. Further studies are necessary to assess clinical outcome, to validate advanced motion management and to explore the benefit of online response adaptive liver SBRT.

MR-Guided Radiotherapy for Rectal Cancer: Current Perspective on Organ Preservation

Online MRI-guided radiotherapy (MRgRT) is one of the most recent technological advances in radiotherapy. MRgRT permits the visualization of tumorous and healthy tissue while the patient is on the treatment table and online daily plan adaptations following the observed anatomical changes. In the context of rectal cancer, online MRgRT is a very promising modality due to the pronounced geographical variability of tumor tissues and the surrounding healthy tissues. This current paper will discuss the possible applications of online MRgRT, in particular, in terms of radiotherapy dose escalation and response prediction in organ preservation approaches for rectal cancer.

Radiogenomics in head and neck cancer: correlation of radiomic heterogeneity and somatic mutations in TP53, FAT1 and KMT2D

PURPOSE

Genetic tumour profiles and radiomic features can be used to complement clinical information in head and neck squamous cell carcinoma (HNSCC) patients. Radiogenomics imply the potential to investigate complementarity or interrelations of radiomic and genomic features, and prognostic factors might be determined. The aim of our study was to explore radiogenomics in HNSCC.

METHODS

For 20 HNSCC patients treated with primary radiochemotherapy, next-generation sequencing (NGS) of tumour and corresponding normal tissue was performed. In total, 327 genes were investigated by panel sequencing. Radiomic features were extracted from computed tomography data. A hypothesis-driven approach was used for radiogenomic correlations of selected image-based heterogeneity features and well-known driver gene mutations in HNSCC.

RESULTS

The most frequently mutated driver genes in our cohort were TP53 (involved in cell cycle control), FAT1 (Wnt signalling, cell-cell contacts, migration) and KMT2D (chromatin modification). Radiomic features of heterogeneity did not correlate significantly with somatic mutations in TP53 or KMT2D. However, somatic mutations in FAT1 and smaller primary tumour volumes were associated with reduced radiomic intra-tumour heterogeneity.

CONCLUSION

The landscape of somatic variants in our cohort is well in line with previous reports. An association of somatic mutations in FAT1 with reduced radiomic tumour heterogeneity could potentially elucidate the previously described favourable outcomes of these patients. Larger studies are needed to validate this exploratory data in the future.

Comparison of treatment plans for a high-field MRI-linac and a conventional linac for esophageal cancer

PURPOSE

To compare radiotherapy treatments plans in esophageal cancer calculated for a high-field magnetic resonance imaging (MRI)-linac with plans for a conventional linac.

MATERIALS AND METHODS

Ten patients with esophageal squamous cell carcinomas were re-planned retrospectively using the research version of Monaco (V 5.19.03, Elekta AB, Stockholm, Sweden). Intensity modulated radiotherapy (IMRT) plans with a nine-field step-and-shoot technique and two-arc volumetric modulated arc therapy (VMAT) plans were created for the Elekta MRI-linac and a conventional linac, respectively. The prescribed dose was 60 Gy to the primary tumor (PTV₆₀) and 50 Gy to elective volumes (PTV₅₀). Plans were optimized for optimal coverage of the 60 Gy volume and compared using dose-volume histogram parameters.

RESULTS

All calculated treatment plans met predefined criteria for target volume coverage and organs at risk dose both for MRI-linac and conventional linac. Plans for the MRI-linac had a lower number of segments and monitor units. No significant differences between both plans were seen in terms of V_20Gy of the lungs and V_40Gy of the heart with slightly higher mean doses to the heart (14.0 Gy vs. 12.5 Gy) and lungs (12.8 Gy vs. 12.2 Gy).

CONCLUSION

Applying conventional target volume and margin concepts as well as dose-fractionation prescription reveals clinically acceptable dose distributions using hybrid MRI-linac in its current configuration compared to standard IMRT/VMAT. This represents an important prerequisite for future studies to investigate the clinical benefit of MRI-guided radiotherapy exploiting the conceptional advantages such as reduced margins, plan adaptation and biological individualization and hypofractionation.

Long-term local control and survival after preoperative radiochemotherapy in combination with deep regional hyperthermia in locally advanced rectal cancer

PURPOSE

The aim of this study was to evaluate the impact of deep regional hyperthermia on long-term local control and survival in locally advanced non-metastatic rectal cancer.

METHODS

In total 103 patients with locally advanced non-metastatic rectal cancer were treated preoperatively with either neoadjuvant radiochemotherapy alone (n = 43) or the same treatment with additional deep regional hyperthermia (n = 60). The two groups were compared with respect to local control, overall survival (OS), disease-free survival (DFS), and distant metastases-free survival (DMFS).

RESULTS

Patients receiving additional hyperthermia had excellent long-term local control with a 5-year Kaplan-Meier estimate of 98% compared with 87% in the radiochemotherapy only group (p = 0.09). Five-year rates for OS (88% versus 76%, p = 0.08), DFS (77% versus 73%, p = n.s.) and DMFS (75% versus 77%, p = n.s.) were not statistically different between the two groups.

CONCLUSION

Radiochemotherapy combined with hyperthermia results in excellent long-term local control.

Magnetic Resonance Guided Radiation Therapy for Pancreatic Adenocarcinoma, Advantages, Challenges, Current Approaches, and Future Directions

Introduction

Pancreatic adenocarcinoma (PAC) has some of the worst treatment outcomes for any solid tumor. PAC creates substantial difficulty for effective treatment with traditional RT delivery strategies primarily secondary to its location and limited visualization using CT. Several of these challenges are uniquely addressed with MR-guided RT. We sought to summarize and place into context the currently available literature on MR-guided RT specifically for PAC.

Methods

A literature search was conducted to identify manuscript publications since September 2014 that specifically used MR-guided RT for the treatment of PAC. Clinical outcomes of these series are summarized, discussed, and placed into the context of the existing pancreatic literature. Multiple international experts were involved to optimally contextualize these publications.

Results

Over 300 manuscripts were reviewed. A total of 6 clinical outcomes publications were identified that have treated patients with PAC using MR guidance. Successes, challenges, and future directions for this technology are evident in these publications. MR-guided RT holds theoretical promise for the treatment of patients with PAC. As with any new technology, immediate or dramatic clinical improvements associated with its use will take time and experience. There remain no prospective trials, currently publications are limited to small retrospective experiences. The current level of evidence for MR guidance in PAC is low and requires significant expansion. Future directions and ongoing studies that are currently open and accruing are identified and reviewed.

Conclusions

The potential promise of MR-guided RT for PAC is highlighted, the challenges associated with this novel therapeutic intervention are also reviewed. Outcomes are very early, and will require continued and long term follow up. MR-guided RT should not be viewed in the same fashion as a novel chemotherapeutic agent for which dosing, administration, and toxicity has been established in earlier phase studies. Instead, it should be viewed as a novel procedural intervention which must be robustly tested, refined and practiced before definitive conclusions on the potential benefits or detriments can be determined. The future of MR-guided RT for PAC is highly promising and the potential implications on PAC are substantial.

Radiation Pneumonitis after Intensity-Modulated Radiotherapy for Esophageal Cancer: Institutional Data and a Systematic Review

Radiation pneumonitis (RP) is a serious complication that can occur after thoracic radiotherapy. The goal of this study is to investigate the incidence of RP after radiochemotherapy with intensity modulated radiotherapy (IMRT) in patients with esophageal cancer and correlate this with dose volume histogram (DVH) related parameters. For this purpose, the clinical course of 73 patients was evaluated and irradiation doses to the lungs were extracted from radiotherapy treatment plans. Furthermore, a systematic review on this topic was conducted across PubMed. In our institutional cohort, Common Terminology Criteria for Adverse Events (CTCAE) grade II or higher RP occurred in four patients (5.5%). The systematic review identified 493 titles of which 19 studies reporting 874 patients qualified for the final analysis. No grade IV or V RP after radiochemotherapy with IMRT for esophageal cancer was reported in the screened literature. Grade II or higher RP is reported in 6.6% of the patients. A higher incidence can be seen with increasing values for lung V20. In conclusion, our institutional data and the literature consistently show a low incidence of symptomatic RP after radiochemotherapy in patients with esophageal cancer treated with IMRT. However, efforts should be made to keep the lung V20 below 23% and specific caution is warranted in patients with pre-existing lung conditions.

Repeatability of diffusion-weighted magnetic resonance imaging in head and neck cancer at a 1.5 T MR-Linac

BACKGROUND AND PURPOSE

Functional information acquired through diffusion-weighted magnetic resonance imaging (DW-MRI) may be beneficial for personalized head and neck cancer (HNC) radiotherapy. Technical validation is required before DW-MRI based radiotherapy interventions can be realized clinically. The aim of this study was to assess the repeatability of apparent diffusion coefficients (ADC) derived from DW-MRI in HNC using echo-planar imaging (EPI) on a 1.5 T MR-Linac.

MATERIAL AND METHODS

A total of eleven HNC patients underwent test/retest DW-MRI scans at least once per week during fractionated radiotherapy at the MR-Linac. An EPI DW-MRI test scan (b=0, 150, 500 s/mm²) was acquired before the start of adaptive MR-guided radiotherapy in addition to an identical retest scan after irradiation. Volumes-of-interest (VOI) were defined manually for parotid (PTs) and submandibular glands (SMs), gross tumor volume (GTV) and lymph nodes (LNs). Mean ADC was calculated for all VOI in all test/retest scans. Absolute/relative repeatability coefficients (RCs/relRCs) as well as intraclass correlation coefficients (ICCs) were determined for all VOI.

RESULTS

A total of 81 datasets were analyzed. Mean test ADC values were 1380/1416, 950/1010, 1520 and 1344·10^-6 mm²/s for left/right SM and PT, GTV and LNs, respectively. Accordingly, RC (relRC) values were determined as 271/281 (19.4/21.8%) and 138/155 (13.3/15.2%), 457 (31.3%) and 310·10^-6 mm²/s (23.5%). ICC resulted in 0.80/0.87, 0.97/0.94, 0.75 and 0.83 for left/right SM and PT, GTV and LNs, respectively.

CONCLUSION

The repeatability of ADC derived from EPI DW-MRI at the 1.5 T MR-Linac appears reasonable to be used for future biologically adapted MR-guided radiotherapy.

Value of PET imaging for radiation therapy

This comprehensive review written by experts in their field gives an overview on the current status of incorporating positron emission tomography (PET) into radiation treatment planning. Moreover, it highlights ongoing studies for treatment individualisation and per-treatment tumour response monitoring for various primary tumours. Novel tracers and image analysis methods are discussed. The authors believe this contribution to be of crucial value for experts in the field as well as for policy makers deciding on the reimbursement of this powerful imaging modality.

Definition, diagnosis and treatment of oligometastatic oesophagogastric cancer: A Delphi consensus study in Europe

BACKGROUND

Local treatment improves the outcomes for oligometastatic disease (OMD, i.e. an intermediate state between locoregional and widespread disseminated disease). However, consensus about the definition, diagnosis and treatment of oligometastatic oesophagogastric cancer is lacking. The aim of this study was to develop a multidisciplinary European consensus statement on the definition, diagnosis and treatment of oligometastatic oesophagogastric cancer.

METHODS

In total, 65 specialists in the multidisciplinary treatment for oesophagogastric cancer from 49 expert centres across 16 European countries were requested to participate in this Delphi study. The consensus finding process consisted of a starting meeting, 2 online Delphi questionnaire rounds and an online consensus meeting. Input for Delphi questionnaires consisted of (1) a systematic review on definitions of oligometastatic oesophagogastric cancer and (2) a discussion of real-life clinical cases by multidisciplinary teams. Experts were asked to score each statement on a 5-point Likert scale. The agreement was scored to be either absent/poor (<50%), fair (50%-75%) or consensus (≥75%).

RESULTS

A total of 48 experts participated in the starting meeting, both Delphi rounds, and the consensus meeting (overall response rate: 71%). OMD was considered in patients with metastatic oesophagogastric cancer limited to 1 organ with ≤3 metastases or 1 extra-regional lymph node station (consensus). In addition, OMD was considered in patients without progression at restaging after systemic therapy (consensus). For patients with synchronous or metachronous OMD with a disease-free interval ≤2 years, systemic therapy followed by restaging to consider local treatment was considered as treatment (consensus). For metachronous OMD with a disease-free interval >2 years, either upfront local treatment or systemic treatment followed by restaging was considered as treatment (fair agreement).

CONCLUSION

The OMEC project has resulted in a multidisciplinary European consensus statement for the definition, diagnosis and treatment of oligometastatic oesophagogastric adenocarcinoma and squamous cell cancer. This can be used to standardise inclusion criteria for future clinical trials.

MRI-Based Upper Abdominal Organs-at-Risk Atlas for Radiation Oncology

PURPOSE

The purpose of our study was to provide a guide for identification and contouring of upper abdominal organs-at-risk (OARs) in the setting of online magnetic resonance imaging (MRI)-guided radiation treatment planning and delivery.

METHODS AND MATERIALS

After a needs assessment survey, it was determined that an upper abdominal MRI-based atlas of normal OARs would be of benefit to radiation oncologists and radiation therapists. An anonymized diagnostic 1.5T MRI from a patient with typical upper abdominal anatomy was used for atlas development. Two MRI sequences were selected for contouring, a T1-weighted gadoxetic acid contrast-enhanced MRI acquired in the hepatobiliary phase and axial fast imaging with balanced steady-state precession. Two additional clinical MRI sequences from commercial online MRI-guided radiation therapy systems were selected for contouring and were included in the final atlas. Contours from each data set were completed and reviewed by radiation oncologists, along with a radiologist who specializes in upper abdominal imaging, to generate a consensus upper abdominal MRI-based OAR atlas.

RESULTS

A normal OAR atlas was developed, including recommendations for contouring. The atlas and contouring guidance are described, and high-resolution MRI images and contours are displayed. OARs, such as the bile duct and biliary tree, which may be better seen on MRI than on computed tomography, are highlighted. The full DICOM/DICOM-RT MRI images from both the diagnostic and clinical online MRI-guided radiation therapy systems data sets have been made freely available, for educational purposes, at econtour.org.

CONCLUSIONS

This MRI contouring atlas for upper abdominal OARs should provide a useful reference for contouring and education. Its routine use may help to improve uniformity in contouring in radiation oncology planning and OAR dose calculation. Full DICOM/DICOM-RT images are available online and provide a valuable educational resource for upper abdominal MRI-based radiation therapy planning and delivery.

Quality assurance of IMRT treatment plans for a 1.5 T MR-linac using a 2D ionization chamber array and a static solid phantom

MR-guided radiotherapy requires novel quality assurance (QA) methods for intensity-modulated radiotherapy treatment plans (TPs). Here, an optimized method for TPs for a 1.5 T MR-linac was developed and implemented clinically. A static solid phantom and an MR-compatible 2D ionization chamber array were used. The array's response with respect to the incident beam gantry angles was characterized for four different orientations of the array relative to the beam. A lookup table was created identifying the optimum orientation for each gantry angle. For the QA of clinical MR-linac TPs, beams were grouped according to their gantry angles and measured with up to four setups. The method was applied to n = 106 clinical TPs of 54 patients for different tumour entities. Reference plans and plans created in the online adaptive workflow were analysed, using a local 3%/3 mm gamma criterion for dose values larger than 30% of the maximum. Pass rates were averaged over all beam groups. The array's response strongly depends on the beam incidence angle. Optimum angles typically range from -10° to 80° around the phantom setup angle. Consequently, plan verification required up to four setups. For clinical MR-linac TPs, the overall median pass rate was 98.5% (range 88.6%-100%). Pass rates depended on the tumour entity. Median pass rates were for liver metastases stereotactic body radiotherapy 99.2%, prostate cancer 99%, pancreatic cancer 98.9%, lymph node metastases 98.7%, partial breast irradiation (PBI) 98%, head-and-neck cancer 97.7%, rectal cancer 94% and others 96.6%. 85% of plans were accepted straightaway, with pass rates above 95%. A single plan with a pass rate below 90% was subsequently verified with a modified method. Off-axis target volumes, e.g. PBI, were verified successfully using a lateral shift of the phantom. The method is suitable to verify reference and online adapted TPs for a 1.5 T MR-linac, including plans for off-axis target volumes.

Deep regional hyperthermia with preoperative radiochemotherapy in locally advanced rectal cancer, a prospective phase II trial

PURPOSE

The goal of the present study was to investigate the effect of deep regional hyperthermia on early and long-term oncological outcomes in the context of preoperative radiochemotherapy in rectal cancer.

METHODS

In this prospective phase II trial, patients with locally advanced rectal cancer were treated with 5-fluorouracil based preoperative radiochemotherapy with 50.4 Gy in 28 fractions. Deep regional hyperthermia was scheduled twice weekly. Pathological tumor regression was scored according to the Dworak regression system. The primary endpoint was pathological complete response (pCR). Further endpoints were local control (LC), distant control (DC), disease-free survival (DFS) and overall survival (OS). Hyperthermia was defined as feasible if 70% of patients received at least eight treatments. Quality of life was assessed at follow-up by the EORTC-QLQ-C30 and QLQ-CR29 questionnaires. Time to event data was analyzed according to Kaplan-Meier based on first-events. The study was registered on clinicaltrials.gov (NCT02353858).

RESULTS

From 2012 until 2017, 78 patients were recruited. Median follow-up was 54 months. Based on magnetic resonance imaging, the mesorectal fascia was involved or threatened in 60% of the patients. Compliance with radiotherapy was 99%, 91% received both cycles of chemotherapy and 77% had eight or more hyperthermia treatments. Median time from the end of radiotherapy to surgery was 6.7 weeks. A pathological complete response was reported in 14% of the patients, 50% had either Dworak 4 (complete regression) or Dworak 3 regression (scattered tumor cells only). Three year estimates for OS, DFS, LC and DC were 94%, 81%, 96% and 87%. Patients with higher hyperthermia related cumulative temperatures showed stronger tumor regression. Global health status based on EORTC-QLQ-C30 was comparable with data from the general population.

CONCLUSION

Deep regional hyperthermia was feasible, did not compromise standard treatments and resulted in promising long-term oncological outcomes and QoL.

RADIANCE - Radiochemotherapy with or without Durvalumab in the treatment of anal squamous cell carcinoma: A randomized multicenter phase II trial

PURPOSE

Anal squamous cell carcinomas (ASCC) are increasing in frequency across the developed world. The 3-year disease-free survival (DFS) in patients with locally-advanced disease is approximately 60% after primary radiochemotherapy (RCT). There is a strong rationale for combining immunotherapy with RCT in patients with ASCC due to its association with human papilloma virus (HPV) infection.

METHODS/DESIGN

RADIANCE is an investigator initiated, prospective, multicenter, randomized phase II trial testing the addition of Durvalumab, a PD-L1 immune checkpoint inhibitor, to standard RCT in 178 patients with locally advanced ASCC (T2 ≥ 4 cm Nany, cT3-4 and/or cN+). In the control arm, patients will be treated with standard mitomycin C (MMC)/5-fluorouracil (5-FU)-based RCT. Intensity-modulated radiotherapy (IMRT) will be applied as follows: PTV_A (primary tumor) T1-T2 < 4 cm N+: 28 × 1.9 Gy = 53.2 Gy; or T2 ≥ 4 cm, T3-4 Nany: 31 × 1.9 Gy = 58.9 Gy; PTV_N (involved node): 28 × 1.8 Gy = 50.4 Gy ; and PTV_Elec (elective node): 28 × 1.43 Gy = 40.0 Gy over a period of 5,5-6 weeks. Concomitant chemotherapy will be administered using MMC with 5-FU during weeks 1 and 5 of radiotherapy (MMC 12 mg/m2, day 1 [maximum single dose 20 mg]; 5-FU 1000 mg/m2 days 1-4 and 29-32). In the experimental arm, Durvalmab (1500 mg absolute dose, intravenously) will be combined with the same RCT as in the control arm. Immunotherapy with Durvalumab will start 14 days before initiation of standard RCT, administered every four weeks (q4w) thereafter for a total of twelve doses. The primary endpoint is disease-free survival (DFS) after 3 years.

DISCUSSION

As ASCC is considered an immunogenically "hot" tumor due to its association with HPV infection, the combination of RCT with Durvalumab may improve tumor control and long-term clinical outcome in this patient collective compared to RCT alone.